Pediatric chronopharmacological findings until now have been limited to circadian changes in children 6 to 15 years old. This means that (a) data in neonates and even in infants of one year is not available and (b) other bioperiodicities with periods of several hours (ultradian rhythms) as well as several months and about one year (infradian rhythms) have not been explored in older children. Biologic time-related changes have been documented for phenytoin and theophylline with regards to pharmacokinetics and for orciprenaline and methylprednisolone with regards to effectiveness (bronchodilatation). Despite the limited number of experiments performed to date, it is already possible to admit that, (a) a chronopharmacological approach provides better precision of pharmacologic study than the conventional approach not using time-related data; (b) better therapeutics can be achieved with the help of chronopharmacological facts since an appropriate timing in administration of a medicine usually enhances its desired effects and/or reduces its undesired effects.